The present invention relates to a fishline length measuring device for a fishing reel, and more particularly relates to a device capable of accurately measuring the unwound and wound lengths of a fishline in terms of the number of the revolutions of the spool of a fishing reel.
A fishing reel developed recently is capable of measuring the unwound and wound lengths of a fishline from and onto the spool of the reel to make it possible to place a fishhook at the depth of the presence of a fish or to detect the distance of the casting of the fishhook to judge where the fishhook has landed on water.
In a conventional device for measuring the unwound and wound lengths of a fishline data on a formula which represents the relationship between the wound quantity of the fishline and the diameter of the winding of the fishline on the spool of a fishing reel and includes the thickness of the fishline as a parameter, and data on the total length of the fishline and so forth are entered into a microcomputer on the body of the reel through a keyboard in advance so that in order to measure the unwound or wound length of the fishline, the rotation of the spool is detected by a sensor, pulses sent out from the sensor are counted by a counter, the count of the counter is entered into the microcomputer at every calculation period, a fishline length calculation formula corresponding to the thickness of the fishline is selected, the unwound or wound length of the fishline is calculated on the basis of the formula, and the result of the calculation is entered into a display unit to digitally indicate the calculated length to the fishing person, as disclosed in the Japan Patent Unexamined Publication No. Sho. 60-244247. However, every time the fishline is replaced with another one, data on the thickness and total length of the latter fishline wound on the spool need to be entered into the microcomputer by manipulating the keyboard. This entering manipulation is troublesome. Since the fishline length calculation formula is a quadratic or cubic equation, it takes much time for the microcomputer to calculate the unwound or wound length of the fishline if the calculation capacity of the microcomputer is low. When the speed of the unwinding of the fishline is high as in the casting thereof, the speed of the calculation of the unwound length of the fishline is lower than the former speed to make it impossible to instantaneously indicate the unwound length changing with the lapse of time. If the fishline length calculation formula is simplified, the length cannot accurately be measured. These are problems.
The present application then developed a fishline length measuring device which is for a fishing reel and does not have those problems. The applicant disclosed the device in the Japan Patent 1-307612. The device includes a sensor for detecting the rotation of the spool of the reel, which is rotatably supported by the body of the reel and on which a fishline is wound, an up/down counter by which pulses sent out from the sensor are counted up or down, a light emitter for irradiating a spot of light upon the surface of the fishline wound on the spool, a fishline winding diameter detector which has a position sensor for detecting the position of a spot of the light reflected by the surface of the wound fishline after being emitted from the emitter and converts the detected position into an electric signal proportional to the diameter of the winding of the fishline, a means for calculating the unwound length of the fishline in terms of the electric signal and the count of the counter, and a display unit for indicating the length calculated by the means. When the light spot is irradiated upon the surface of the wound fishline on the spool by the light emitter, the position of the spot of the light reflected by the surface after being emitted from the emitter is detected by the position sensor of the fishline winding diameter detector and then converted into the electric signal proportional to the diameter of the winding of the fishline on the spool. The unwound length of the fishline from the spool is calculated by the means in terms of the signal and the count of the counter, which corresponds to the number of the revolutions of the spool in the unwinding or winding of the fishline. The unwound or wound length of the fishline can thus be quickly and accurately determined. Besides, since parameters such as the thickness and total length of the fishline are not needed for the determination, the manipulating property of the device if higher.
Since the spot of the light is irradiated upon the surface of the fishline on the spool by the fishline length measuring device disclosed in the above-mentioned Application No. Sho. 63-137764, the light emitted from the light emitter such as a light emission diode and a semiconductor laser element needs to be converged on the surface of the fishline by an optical unit such as a lens. The light reflected by the surface of the wound fishline on the spool after being emitted from the emitter also needs to be converged on the position sensor by another optical unit. Because of the presence of the optical units, it is very difficult to make the sensor section of the fishline winding diameter compact. Since the range of the diameter of the winding of the fishline, which can be measured through the use of a single optical unit, is limited, the unit needs to be replaced depending on the size of the reel. These are problems.